File names appended with ~ plus alphanumeric characters
 

-Within the last few days all of my file names have the xlss extension plus
another with a ~ plus additional characters.
Also when I go to open my files with just the xlss extension I get the
message "the file is not in the same format , do I want to open it anyway? "
paraphrased. I open the file and so far they have all been what I was
expecting.
Just learning